[Android Q&A, Help & Troubleshooting] peido:
I had a problem yesterday while trying to unbrick my LG C660 (only Emergency Mode worked, if not in Emergency Mode my phone would stay in the LG logo forever and ever, I bricked it by selecting Backup using Rom Manager after installing ClockworkMod) and it took me the whole day to find a solution. Might help somebody else in the future.

I was trying to flash my LG C660, with the phone in Emergency Mode I connected it to the USB cable and started KDZ UPDATER. KDZ UPDATER would detect the phone and start the process, but after a few moments the phone would reboot and stay forever in the LG logo, after about 5 minutes the process would fail.

My log was:

[22:18:31:625] : =============================================

[22:18:31:625] : Log is started on 28.12.2015, at 22:18:31:625,

executable: E:\LG Optimus Pro (C660)\KDZ_FW_UPD.exe (ProcID: 0x000003d4),

compile time : Jan 19 2012 09:29:39

[22:18:31:625] : Version :

[22:18:31:625] : Get Usb Port

[22:18:31:629] : rsi.strFriendlyName=Porta de comunicações (COM1)

[22:18:31:629] : Remove Porta de comunicações (COM1)

[22:18:31:629] : rsi.strFriendlyName=LGE Android Platform USB Serial Port (COM4)

[22:18:31:629] : FriendlyNameList[iii].szFriendlyName=LGE Android Platform USB Serial Port

[22:18:31:629] : WM_COPYDATA ¸Þ½ÃÁö º¸³¿ 1 - COM4

[22:18:31:629] : Port = COM4

[22:18:31:632] : UNKNOWN : Req(12) -> Rsp(13)

[22:18:31:634] : UNKNOWN : Req(12) -> Rsp(13)

[22:18:31:636] : UNKNOWN : Req(12) -> Rsp(13)

[22:18:31:636] : >> DIAG_STATUS_F FAILED

[22:18:31:642] : >>Get Model Name [DIAG_VERNO_F]

[22:18:31:644] : BAD CONN MODE : Req(0) -> Rsp(3)

[22:18:31:646] : BAD CONN MODE : Req(0) -> Rsp(3)

[22:18:31:648] : BAD CONN MODE : Req(0) -> Rsp(3)

[22:18:31:650] : BAD CONN MODE : Req(0) -> Rsp(3)

[22:18:31:652] : BAD CONN MODE : Req(0) -> Rsp(3)

[22:18:31:654] : BAD CONN MODE : Req(0) -> Rsp(3)

[22:18:31:654] : FAIL (No Phone)

[22:18:31:654] : GetModelName() Operation Failed Check Diag CMD

[22:18:31:654] : EMERGENCY Booting Mode

[22:18:31:654] : >>Get Model Name in Emergency Mode [DLOAD_VERREQ_F]

[22:18:31:656] : BS/C660/7Dmg

[22:18:31:656] : WM_COPYDATA ¸Þ½ÃÁö º¸³¿ 0 - C660

[22:18:31:656] : _Reset_N_Close bFirst = 3

[22:18:31:656] : ¸Þ½ÃÁö º¸³¿ TYPE_WPARAM_RESET_THE_PHONE_1ST 8

[22:18:31:656] : [COM4] Reset [DLOAD]

[22:18:31:656] : WM_COPYDATA ¸Þ½ÃÁö º¸³¿ 3 - RESET

[22:18:31:957] : DIAG_DLOAD_F DLOAD_RESET_F do not wait for response

[22:18:32:257] : WM_COPYDATA ¸Þ½ÃÁö º¸³¿ 3 - Close Port

[22:18:32:257] : Close Port<<

[22:25:12:257] : OPEN_PORT_FAIL

[22:25:12:257] : TYPE_WPARAM_UPGRADE_ERROR

[22:25:12:257] : ¸Þ½ÃÁö º¸³¿ - TYPE_WPARAM_UPGRADE_ERROR Error Code = 6

[22:25:12:289] : Log finished

To bypass the problem I did the following: Start phone in Emergency Mode, Connect phone to PC using USB cable, Start KDZ UPDATER and start process, has soon has the phone reboots and stays forever in the LG logo I would disconnect the USB cable, remove the battery, insert the battery, restart the phone in Emergency Mode, connect the USB cable. As soon as I did this, KDZ UPDATER continued the process and after a few minutes everything ended successfully.

Don't forget to make sure that all LG modems in the Windows device manager are inactive. Don't forget to install the LG drivers (LG PC Suite can be installed for that). Remove SD and SIM cards. In KDZ UPDATER, PHONE MODE can be set to EMERGENCY instead of DIAL. Execute KDZ UPDATER as Administrator. Instead of pressing Vol.Up+Return+Power with the phone off to go into Emergency Mode, you can also press Vol.Up+Return and connect the phone to the USB cable with the phone off to start Emergency Mode.

Managed to flash firmware V10D (Jan.2012, Android 2.3.4) using Windows 7 32bits.

Thanks to Claudiow in another forum for finding the solution to this problem with a LG P698 and to raimundex from that same forum.